1. Field of the Invention
The present invention relates to a holding tank, and more particularly, to the type that is used in continuous flow processing of milk.
2. Description of the Related Art
The processing of liquids, and in particular milk, requires inter alia exposure to predetermined temperatures over a given time period. For pasteurizing milk in a modern continues flow process the milk is typically exposed to a relatively high temperature (72.degree. to 75.degree. C.) for a relatively short time (16 seconds). And this is referred to as the HTST (High Temperature Short Time) method.
Another method for pasteurizing milk is known as the LTH (Low Temperature Long Time) method wherein the milk is held for 30 minutes at a relatively lower temperature of 63-65.degree. C. Both processes have their advantages and disadvantages.
The longer holding time of the latter method, however, makes it impractical for use in continuos flow processes since it would require an extraordinarily long conduit. Thus, the desirability of having a device that can provide a variable holding time in a continuous flow environment. Furthermore, it is also desirable that this device be capable of readily changing the holding time as required or desired. The present invention provides the user with this flexibility permitting the immediate adjustment of holding times to achieve the projected output characteristics.
The closest reference known to applicant corresponds to German patent No. 343,889 issued in 1921. Basically, the heating unit of the foreign patentee utilizes chambers with smaller diameters (for faster flow) where the milk rises to prevent the heavier solids from separating. The only concern in that patented invention was to mechanically prevent the settlement of the heavier particles. In the present invention there is no preferential flow and the milk follows the first in, first out rule. More important, the foreign patent does not disclose level sensors or any other mechanisms for changing the holding time.